Apparatus for grading powdered material



Patented July 25, 1944 UNITED STATE APPARATUS FOR GRADING POW'DEBED MATERIAL Walter Fred Harlow,

or to International Quarndon, England, assign- Combustion Limited, London, England, a British company Application January 11,1943, Serial No. 412,031

i In Great Britain March 18, 1942 '1 Claim. (01. 83-93) or mill a. With the arrangement described it is The present invention relates to apparatus vwhich comprises two superposed cyclones associated with a mill equipped with a primary separator which delivers material into the grading device, the line products passing to acollector, and the returned air from the collector passing to a fan and thence to the mill so that a closed circuit is obtained.

. In order to restrict as far aspossible the quantity of vented air employed, air is in this arrangement admitted to a housing surrounding the air admission ports described in my application Serial Number 472,030; filed January 11,1943, this housing embracing the ing connected by a pipe admission ports, and beto the dischargeside oi the fan. This arrangement obviates the necessity for the admission of atmospheric air.

Oneform of construction of the invention is illustrated diagrammatically in the annexed drawing. In this drawing, a is a mill equipped with a primary separator, and delivering into a cyclone device b of the kind described in'application Serial Number 472,i)30,, flied January 11, 1943, the line products passing toa collector c, and the returned air passing to a fan d, and thence back, to the mill a so that a closed circuit is obtained. The direction of travel of the products. and of 'the air is indicated by the arrows .on the drawing. The coarse products reiected'bythe separator are delivered to a chute I by which the raw material to be pulverised is led to'the pulveriser vent dust emission,

- I claim:

Iii

prising, a mill equipped with a rimary separa necessary to vent the system of surplus air'at a suitable point so as to maintain a vacuum to prethe vented air being passed through a bag filter at As it is of importance to restrict the amount of vented air as far as possible in order to restrict thelize or the filtering apparatus, which is an expensive one, it is desirable to prevent the entry of atmospheric air into the system. For this ports a' of the lower cyclone s is connected by a pipe chargeside oi the tan d.

Apparatus for grading powdered material com- ,tor, a grading device formed or cyclone separators, a conduit for guiding material from the pri-' 'mary separator into the grading device, a collector, a pipe guiding fine particles irom the grading device into the collector, a fan. a conduit connecting the fan with the collector whereby air is drawn from the collector, a discharge tube connecting the fan with the mill whereby air drawn from the collector cyclone separator having air admission ports therein, a housing embracing pipe connecting the housing with the discharge tube from the ian whereby a portion oi air delivered by the tan is-supplied to the admission ports.

purposev a housing em-- bracing the air admission h to the disis suPpiiedto the mill, onesaid ports. and a ,wwrsaraspmatow. v 

